Joint Program in Nuclear Medicine

The Scintigraphic Evaluation of Focal Nodular Hyperplasia with Tc-99m Sulfur Colloid

Jac D. Scheiner, MD 
J. Stevan Nagel, MD

January 14, 1997

Presentation

A 28 year old female presented with abdominal pain. Ultrasound of the abdomen demonstrated an approximately 9 by 9 cm echogenic mass comprising most of the left hepatic lobe (shown by markers). Computed tomography (CT) of the liver showed a mass corresponding to the ultrasound findings in the left hepatic lobe, but was otherwise normal. The mass was of a near homogeneously higher attenuation than the liver on the contrasted CT images.

Imaging Findings

A Tc-99m sulfur colloid exam (anterior planar image and SPECT images) demonstrated uptake in this lesion that was of a higher intensity than the rest of the liver (arrow on planar and on SPECT images). This finding proved that the lesion was benign, most likely focal nodular hyperplasia.

Diagnosis

Focal Nodular Hyperpasia

Discussion

Focal nodular hyperplasia is a benign tumor of the liver with no malignant potential. On pathology, the lesion appears as a focal proliferation of normal hepatic tissue (hepatocytes, bile ducts, and Kupffer cells). Complications from this lesion are exceedingly rare, but include bleeding and infarction (1).

Differential Diagnosis

The main differential diagnosis of a solid hepatic lesion on CT in an otherwise healthy young female is hepatic adenoma. Cavernous hemangioma another common hepatic lesion usually has characteristic findings on CT. Distinguishing focal nodular hyperplasia and adenoma is important because hepatic adenoma's can result in fatal hemorrhage, and must be resected. A series of all patients with focal nodular hyperplasia (FNH) and all patients with hepatic adenoma (HA) seen at the Mayo Clinic from 1961-1980 provided the following data (2):
FNH HA 
# patients 41 23 
% female 88% 91% 
% on oral contraceptive pill
or supplemental estrogen 		 58% 89% 
age (years) 41 +/- 2 34 +/- 2 
Patient demographic data and history tend to be of little use in distinguishing these two entities. CT, ultrasound, and magnetic resonance imaging (MRI) are generally not specific for either diagnosis.

Liver scintigraphy using Tc-99m sulfur colloid provides a highly specific method for diagnosing focal nodular hyperplasia. The characteristic findings are a lesion, corresponding to a solid lesion on CT, ultrasound, or MRI, that has uptake greater than or equal to the rest of the liver. The differential diagnosis of a hot spot on Tc-99m sulfur colloid liver scintigraphy would include:

False Positive Studies

False positive Tc-99m sulfur colloid scans for focal nodular hyperplasia have reported in which the final diagnosis was hepatoblastoma (3 cases) (6,7) or hepatic adenoma (4 cases) (8,9). Although these lesions took up Tc-99m sulfur colloid, none of these cases had uptake greater than the liver. In addition, at most 2 cases had uptake equal to the liver, both of which were adenomas.

Etiology of Increased Uptake

The cause of the relatively increased Tc-99m sulfur colloid uptake in focal nodular hyperplasia, as opposed to hepatic adenoma, remains controversial. Classic teaching is that hepatic adenoma's tend to be cold because they do not contain Kupffer cells (the main functional cell of the reticular endothelial system that takes up colloid). However, a review by the Armed Forces Institute of Pathology demonstrated Kupffer cells in 12 hepatic adenomas (8). Two of the 12 adenomas had uptake less than or equal to normal liver, and both had a normal number of Kupffer cells relative to normal liver. The remaining 10 adenomas were cold on Tc-99m sulfur colloid scans. Six of these 10 had a normal number of Kupffer cells relative to normal liver, whereas the remaining 4 had a decreased number of Kupffer cells.

The exact cause of the differential Tc-99m sulfur colloid uptake remains unclear, although the etiology is likely related to a combination of factors such as differences in the number of Kupffer cells in these lesions, the functionality of Kupffer cells in these lesions, and/or differences in blood flow.

Decreased Uptake in Focal Nodular Hyperplasis It is important to note than approximately 37% of focal nodular hyperplasia will be cold on Tc-99m sulfur colloid scans (10). The sensitivity of Tc-99m sulfur colloid for detecting an focal nodular hyperplasia as being of an intensity greater than or equal to the liver has been reported to be approximately 63% (7% greater than liver, 56% equal to liver). However, all of the published data has been based on planar imaging.

Summary

On scintigrams using Tc-99m sulfur colloid, a lesion that is of increased or equal intensity relative to normal liver should be left alone. In patients without a history of cirrhosis or venous occlusive disease, the diagnosis is focal nodular hyperplasia over 99% of the time.

References

1. AJR 131:393-402, 1978

2. Gastroenterology 84:994-1002,1983

3. Radiology 107:257-263,1973

4. JNM 30:113-116, 1989

5. JNM 28:803-809, 1987

6. Clin Nucl Med 16:236-238, 1991

7. AJR 139:168-171, 1982

8. AJR 148:1105-1108, 1987

9. AJR 113:56-60,1971

10. AJR 137:983-990, 1981

Click here to go to Joint Program in Nuclear Medicine home page and Copyright notice. 
J. Anthony Parker, MD PhD, Tony_Parker@bidmc.harvard.edu